1. Field of the Invention
The present invention relates to a door checker for an automobile, and particularly to an improvement in a door checker for an automobile, comprising: a case secured to a door turnably supported on a body of an automobile; a check lever which is swingably supported on said body to extend through said case and which has a ball guide groove formed in its side face to extend in a lengthwise direction; a ball holder accommodated in said case and capable of being moved toward and away from the side face of said check lever; a check ball retained in said ball holder and capable of being rolled in said ball guide groove; and a check spring for biasing said ball holder toward said ball guide groove; said check lever having an intermediate recess which is formed in its side face and deeper than said ball guide groove, and into which said check ball is fitted by a biasing force of said check spring in order to generate a moderation resistance in a position of at least one medium opening degree.
2. Description of the Related Art
A conventional door checker for an automobile is disclosed, for example, in Japanese Utility Model Publication Laid-open No. 58-20059.
The intermediate recess in the check lever of the conventional door checker for the automobile forms a portion of a spherical surface having a diameter equal to or slightly larger than that of the check ball.
The setting of the diameter of the spherical surface corresponding to the intermediate recess in the check lever at the value substantially equal to that of the check ball, as described above, is effective for making clear a feeling of moderation at a predetermined medium opening degree at which the door should be stopped and retained and which is provided by the fitting between the recess and the check ball. However, this is one of causes which generate an abnormal sound when the check ball is passed through the intermediate recess by rapidly opening or closing the door.
More specifically, if the spherical surface corresponding to the intermediate recess and the check ball have substantially the same diameter, the check ball is brought into a no-load state due to the delay of the following of the check spring and the ball holder, the moment the check ball is dropped rapidly into the intermediate recess. Therefore, the check ball immediately collides with an upward slope of the intermediate recess due to an inertial force without reaching a bottom surface of the intermediate recess, and the resultant percussive noise resonates with the case and the door to generate an abnormal sound.
Therefore, if the diameter of the spherical surface corresponding to the intermediate recess is set at a value sufficiently larger than that of the check ball, the check ball reaches the bottom surface of the intermediate recess and climbs the upward slope of the intermediate recess, while being rolled on the upward slope, after the delay of the following of the check spring and the ball holder. Therefore, the generation of an abnormal sound due to the shock as described above does not occur. However, this is accompanied by a disadvantage that the feeling of moderation upon stopping and retaining the door at the predetermined medium opening degree is deteriorated in an amount corresponding to an increase in diameter of the spherical surface corresponding to the recess.
The present invention has been accomplished with such circumstance in view, and it is an object of the present invention to provide a door checker for an automobile, which can prevent the generation of an abnormal sound when the check ball is passed through the intermediate recess by rapidly opening or closing the door, while improving the feeling of moderation upon fitting between the check ball and the intermediate recess.
To achieve the above object, according to a first feature of the present invention, there is provided a door checker for an automobile, comprising: a case secured to a door turnably supported on a body of an automobile; a check lever which is swingably supported on said body to extend through said case and which has a ball guide groove formed in its side face to extend in a lengthwise direction; a ball holder accommodated in said case and capable of being moved toward and away from the side face of said check lever; a check ball retained in said ball holder and capable of being rolled in said ball guide groove; and a check spring for biasing said ball holder toward said ball guide groove; said check lever having an intermediate recess which is formed in its side face and deeper than said ball guide groove, and into which said check ball is fitted by a biasing force of said check spring in order to generate a moderation resistance in a position of at least one medium opening degree; wherein said intermediate recess is formed so that a second opening width in a direction intersecting a centerline of said ball guide groove is larger than a first opening width along said centerline of said ball guide groove.
With the first feature, the sectional shape of the intermediate recess along the centerline of the ball guide groove is formed substantially in correspondence to the sectional shape of the check ball, whereby the movement of the check ball in the direction along the ball guide groove while being fitted in the intermediate recess can be properly restrained by the intermediate recess, thereby providing a definite feeling of moderation to a user and preventing a large shaking of the door.
If the check ball is vigorously passed through the intermediate recess with the rapid opening or closing operation of the door, a distance of movement of the check ball in the intermediate recess can be ensured by the inertial force, even when the check ball is brought into a no-load state in the intermediate recess due to the delay of response of the check spring and the ball holder. As a result, the check ball is dropped onto a bottom surface of the intermediate recess by the retarded urging actions of the check spring and the ball holder, and then climbs an upward slope of the intermediate recess while being rolled on the upward slope. Thus, it is possible to avoid the collision of the check ball with upward slope of the intermediate recess to prevent the generation of an abnormal sound due to the collision.
According to a second feature of the present invention, in addition to the first feature, the intermediate recess is of a shape formed by elongating a recess formed by a portion of a virtual spherical surface having a diameter substantially equal to a diameter of the check ball, away from the center line of the ball guide groove in a direction intersecting the centerline.
With the second feature, the shape of the intermediate recess is simplified, and the intermediate recess can be formed easily. In addition, it is possible to reliably prevent the generation of an abnormal sound, while ensuring a good feeling of moderation.